Weight reduction of gas permeation preventing structures used in applications which require the prevention of gas permeation (for example, pneumatic tires, gas or fluid transporting hoses, etc.) has heretofore been desired. Generally, the amount of gas (for example, air) that passes through a layer of a thermoplastic resin composition or rubber composition decreases with the increase in the thickness of that layer. However, since the weight of the layer increases with the increase in the thickness of the layer, in applications, such as pneumatic tires, in which weight reduction is required in order to improve fuel efficiency, there have been many proposals for reducing the weights of the gas permeation preventing structures by using a material having high gas barrier properties (i.e., a material having a low gas permeation coefficient). For example, using a laminate comprising a gas permeation preventing layer comprising a thermoplastic resin such as ethylene-vinyl alcohol copolymer (EVOH), which is known to have excellent gas barrier properties and an elastic surface layer or adhesive layer comprising a rubber or thermoplastic elastomer, etc., as an inner liner provided on the inner surface of a pneumatic tire to retain the inner pressure of the pneumatic tire is proposed in, for example, Japanese Unexamined Patent Publication (JP-A) No. 1-314164, Japanese Unexamined Patent Publication (JP-A) No. 6-40207, WO 2007/083785, WO 2007/100159, and WO 2007/123220.
However, when an EVOH-containing layer is applied to the inner surface of a tire as a laminate with another layer having a low elastic modulus, such as a rubber layer, as proposed in the above patent documents, or when an EVOH-containing layer is directly applied to the inner surface of a tire, since EVOH has a significantly higher elastic modulus compared to rubber usually used in pneumatic tires, excessive stresses due to repeated, flex and tensile deformations during tire running are applied to the EVOH-containing layer, and as a result, cracks may occur in the EVOH-containing layer. The more the EVOH-containing layer tends to generate cracks, the less the fatigue durability, and therefore the less the air pressure retaining properties.
Accordingly, in the laminate comprising an EVOH-containing layer, it is necessary to have well balanced gas permeation preventing properties and fatigue durability (consequently air pressure retaining properties) by preventing the cracking of the EVOH-containing layer from occurring.